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Vanadium
Vanadium is the chemical element with the symbol V and atomic number 23. It is a soft, silvery grey, ductile transition metal. The formation of an oxide layer stabilizes the metal against oxidation. Andrés Manuel del Río discovered vanadium in 1801 by analysing the mineral vanadinite, and named it erythronium. Four years later, however, he was convinced by other scientists that erythronium was identical to chromium. The element was rediscovered in 1831 by Nils Gabriel Sefström, who named it vanadium after the Scandinavian goddess of beauty and fertility, Vanadis (Freya). Both names were attributed to the wide range of colors found in vanadium compounds. The element occurs naturally in about 65 different minerals and in fossil fuel deposits. It is mainly used to produce specialty steel alloys such as high speed tool steels. The compound vanadium pentoxide is used as a catalyst for the production of sulphuric acid. Vanadium is found in many organisms, and is used by some life forms as an active center of enzymes. Characteristics It has good resistance to corrosion and it is stable against alkalis, sulphuric and hydrochloric acids. It is oxidized in air at about 933 K (660 °C, 1220 °F), although an oxide layer forms even at room temperature. Naturally occurring vanadium is composed of one stable isotope 51V and one radioactive isotope 50V. The latter has a natural abundance 0.25%. 51V has a nuclear spin of 7/2 which is useful for NMR spectroscopy. A number of 24 artificial radioisotopes have been characterized, ranging in mass number from 40 to 65. The most stable of these isotopes are 49V with a half-life of 330 days, and 48V with a half-life of 15.9735 days. All of the remaining radioactive isotopes have half-lives shorter than an hour, most of which are below 10 seconds. At least 4 isotopes have metastable excited states. Electron capture is the main decay mode for isotopes lighter than the 51V. For the heavier ones, the most common mode is beta decay. The electron capture reactions lead to the formation of element 22 (titanium) isotopes, while for beta decay, it leads to element 24 (chromium) isotopes. The chemistry of vanadium is noteworthy for the accessibility of four adjacent oxidation states. The common oxidation states of vanadium are +2 , +3 , +4 and +5. Vanadium(II) compounds are reducing agents, and vanadium(V) compounds are oxidizing agents. Vanadium(IV) compounds often exist as vanadyl derivatives which contain the VO2+ center. Ammonium vanadate(V) (NH4VO3) can be successively reduced with elemental zinc to obtain the different colors of vanadium in these four oxidation states. Lower oxidation states occur in compounds such as V(CO)6, V(CO)6− and substituted derivatives. The vanadium redox battery utilizes these oxidation states; conversion of these oxidation states is illustrated by the reduction of a strongly acidic solution of a vanadium(V) compound with zinc dust. The initial yellow color characteristic of the vanadate ion, VO3−4, is replaced by the blue color of VO(H2O)52+, followed by the green color of V(H2O)63+ and then violet, due to V(H2O)62+. The most commercially important compound is vanadium pentoxide, which is used as a catalyst for the production of sulphuric acid. This compound oxidizes sulphur dioxide (SO2) to the trioxide (SO3). In this redox reaction, sulphur is oxidized from +4 to +6, and vanadium is reduced from +5 to +3. Value The base value of each unit of ranges between 5 and 20Ð per unit, with up to 5 units being found at any one time. Presence on Mars: Common Category:Chemical elements